We coated the grout on our tiled hearth with silicone to protect it from staining and to make cleaning easier. Normally, this solution is applied with a sponge brush. However, I’ve found a better way. I put the solution in a glue bottle whose application tip has a very small hole. I then flood the grout line using this bottle. The grout soaks up the solution very quickly, so I keep applying the solution until it no longer soaks into the grout. This technique makes for a much quicker and more thorough job. If any excess silicone remains on top, I wipe it off with a clean cloth.
Neil Hartzler, Colorado Springs, CO